Field of the Invention
The present invention relates to an image display apparatus, an image output apparatus, and control methods therefor.
Description of the Related Art
A multi-screen display system (a multi-image display apparatus) is widely adopted in which a plurality of image display apparatuses (hereinafter referred to as displays) are arranged longitudinally and laterally (in a matrix shape) adjacent to one another and connected to one another to configure one image display apparatus as a whole (see, for example, Japanese Patent Application Laid-Open No. 2012-58475). In the following explanation, display of an image in the multi-screen display system is referred to as multi-screen display. As the image display apparatus used in the multi-screen display system, a liquid crystal display is often adopted from the viewpoint of a reduction in weight and thickness, installability, and the like.
In Video Electronics Standard Association (VESA), which is an industry standardization organization concerning moving image related apparatuses, a standard concerning the multi-screen display system is proposed. In the proposal, a connection configuration and arrangement information of a display is described in a Display ID transmitted by a sync apparatus (a display) to enable a source apparatus side (an image output apparatus such as a PC) to grasp the configuration of the multi-screen display system.
In the liquid crystal display, there is a technique for controlling, for each of a plurality of control regions configuring a screen, according to input image data, light emission brightness of a light source of a backlight configured by a light emitting diode (LED) or the like. Further, there is a technique for controlling, for each of control regions, light emission brightness of a light source of a backlight according to input image data and correcting the image data according to a level of the light emission brightness. These techniques are called local dimming. By using the local dimming techniques, it is possible to improve contrast of image display and suppress floating black.